Iron-type golf club heads may generally be classified into “blade” and “perimeter-weighted” categories. Perimeter-weighted iron-type golf club heads may have a substantial concentration of mass distributed behind the striking surface in the form of at least one peripheral wall, sometimes called the perimeter-weighting element. A perimeter-weighted iron-type golf club head may also be referred to as a “cavity-back” iron head, or simply a “cavity-back”, because the perimeter-weighting element thereof generally delimits a cavity in the rear portion of the club head opposite the striking face.
Perimeter-weighted irons are typically more “forgiving” than those of the blade type because the elevated moment of inertia generally associated with perimeter-weighted designs results in decreased head rotation when a ball is mishit, or struck away from the point of orthogonal projection of the club head's center of gravity onto the striking surface of the iron. Diminished rotation of the club head at impact may increase the accuracy and distance of such mishit shots. Thus, perimeter-weighted irons may substantially benefit less skilled golfers, who are likely to mishit the ball.
Various improvements for cavity-back iron heads, such as localized mass concentrations along the perimeter-weighting element, have been proposed. For example, it is well known that lowering the club head's center of gravity generally increases ball-launch angle at impact, thus facilitating shots from a variety of lies. Accordingly, sole-weighted cavity-back iron heads help improve ball-launch conditions.
In addition to mass-distribution improvements, a variety of vibration-attenuation technologies have been proposed for cavity-back irons. Some examples comprise a constrained-layer damper positioned behind the striking face within the rear cavity. Others include a resilient insert centrally disposed in the rear cavity. Typically, such inserts are made from materials having vibration-damping characteristics and low density.
However, club heads comprising a resilient insert located in the rear cavity may lack sufficient tactile feedback for a player to distinguish a well-made shot from a mediocre one. In addition, even though club heads fitted with constrained-layer dampers provide abatement of undesirable dynamic-excitation-response modes for a range of mishit shots, unfavorable dynamic-excitation-response modes associated with, e.g., extreme heel and toe mishits for such club heads remain problematic.